Evasion of the immune system

Question 1

What properties allow rapid evolution of pathogens?

Answer 1

Short life cycle and ability to mutate rapidly

Question 2

Antigenic drift vs antigen shift?

Answer 2

Drift = mutations in gene encoding viral envelope antigens = small changes, low chance of pandemic
Shift = radically different strain due to recombination of viral genome between avian and human viruses - so no immune response

Question 3

How does herpes simplex evade the immune system?

Answer 3

Invades neurones which have very few MHC class I

Question 4

Bacterial superantigens

Example

Answer 4

Antigens that bind MHC and TCR independent of antigen specificity leading to an excessive polyclonal T cell response leading to excessive release of cytokines = toxic shock syndrome